1. Field of the Invention
The present invention relates to the field of content protection. More specifically, the present invention addresses the provision of protection to digital video content to facilitate their secure transmission from a video source device to a video sink device.
2. Background Information
In general, entertainment, education, art, and so forth (hereinafter collectively referred to as xe2x80x9ccontentxe2x80x9d) packaged in digital form offer higher audio and video quality than their analog counterparts. However, content producers, especially those in the entertainment industry, are still reluctant in totally embracing the digital form. The primary reason being digital contents are particularly vulnerable to pirating. Unlike the analog form, where some amount of quality degradation generally occurs with each subsequent copy, a pirated copy of digital content is virtually as good as the xe2x80x9cgold masterxe2x80x9d. As a result, much effort has been spent by the industry in developing and adopting techniques to provide protection to the distribution and rendering of digital content.
Historically, the communication interface between a video source device (such as a personal computer) and a video sink device (such as a monitor) is an analog interface. Thus, very little focus has been given to providing protection for the transmission between the source and sink devices. With advances in integrated circuit and other related technologies, a new type of digital interface between video source and sink devices is emerging. The availability of this type of new digital interface presents yet another new challenge to protecting digital video content. While in general, there is a large body of cipher technology known, the operating characteristics such as the volume of the data, its streaming nature, the bit rate and so forth, as well as the location of intelligence, typically in the source device and not the sink device, present a unique set of challenges, requiring novel solutions.
A video source device provides a basis value to a symmetric ciphering/deciphering process to a video sink device, to which the video source device is to provide video content. The video source device ciphers the video content for transmission to the video sink device, including generation of a first cipher key through functional transformation of the basis value. The video source device further verifies periodically that the transmitted video content is indeed being symmetrically deciphered by the video sink device.